The present invention relates to labeled compounds and more particularly to compounds labeled with carbon-13 and hydrogen-2.
Stable isotope labeled amino acids and nucleotides are required for structural and mechanistic studies of proteins and oligonucleotides. In addition, isotopically labeled biologically active compounds are required for many phases of drug discovery and development including elucidation of biosynthetic pathways, pharmacokinetics, and drug metabolism. For many applications, site-specific 13C or combined 13C and 2H labeling are required. While a number of stable isotope labeled compounds are available from companies such as Sigma-Aldrich Chemicals, a need remains for other labeled synthetic precursors.
Dithane has been used in a wide number of reactions to make a large number of such biomolecules and other important synthetic precursors. For example, dithane can be used as a nucleophilic synthon. While dithane could provide a chemically stable and non-volatile carrier for the valuable 13C and 2H labels, the preparation of isotopically labeled dithane has not been previously accomplished. Thus, availability of 2H- and 13C-substituted dithanes would allow researchers to take advantage of the wealth of chemistry that has been done using unlabeled methyl phenyl sulfide.
As carbon-13 is separated from its lighter isotope by cyrogenic distillation of carbon monoxide (CO), all labeled carbons are derived ultimately from CO. The highly efficient conversion of CO to useful chemical precursors is perhaps the most unique aspect of stable isotope labeling technology. Any inefficiencies in the early synthetic steps add greatly to the overall expense of isotope labeling. Thus, considerable efforts have been directed to the development of methods for the preparation of useful synthetic precursors or synthons. This effort has given rise to efficient large-scale methods for the synthesis of methane, methanol, methyl iodide, sodium formate, potassium cyanide and carbon dioxide. These methods are the foundation of all labeling chemistry. The most useful of the electrophilic one-carbon precursors, methyl iodide and carbon dioxide, are difficult to store and use efficiently due to their high volatility.
As spectroscopic instrumentation and techniques continue to improve, there is a drive to study ever more complicated bio-systems. This has lead to demands for more complex labeling patterns in biomolecules. In the past, the simple introduction of a labeled atom site-specifically without stereospecificity was the major thrust for stable isotope labeling and the first generation of labeled synthons served this effort well. Increasingly, in today""s labeling climate, in addition to site-specific labeling, the requirement for stereospecificity has been added. This includes both the ability to stereospecific label chiral compounds as well as the ability to differentiate between prochiral centers with deuterium or carbon. Additional synthons as starting materials will address those growing demands.
It is an object of the present invention to provide labeled compounds.
In accordance with the purposes of the present invention, as embodied and broadly described herein, the present in invention provides the labeled compound, [2-13C]dithane wherein the 13C is directly bonded to exactly one or two deuterium atoms.
The present invention further provides a process of preparing compounds such as [2, 2-2H2, 2-13C]dithane by reacting [2H3, 13C]methyl phenyl sulfoxide with sodium acetate to form an intermediate product; and, reacting said intermediate product with HSxe2x80x94(CH2)3xe2x80x94SH to form [2, 2-2H2, 2-13C]dithane.
The present invention still further provides labeled compounds, of the structure Arxe2x80x94Sxe2x80x94C*D2-xHxxe2x80x94Oxe2x80x94R where Ar is an aryl group, C* is a 13C labeled carbon atom, D is a 2H, x is 0 or 1, and R is selected from a C1-C5 lower alkyl group or an acyl group including a C1-C5 lower alkyl group substituent, i.e., the acyl group is (xe2x80x94C(O)R1) where R1 is a C1-C5 lower alkyl. In a preferred embodiment, R is an acyl group wherein R1 is methyl such that the labeled compounds are [2H1-2, 13C]methanol(arylthio)-, acetates wherein said 13C atom is directly bonded to exactly one or two deuterium atoms.
Dithane is a useful organic reagent that allows for the construction of many useful biochemicals and materials. Isotopically labeled dithane can be used to introduce a carbon-13 and a hydrogen-2 or deuterium label [2H] into such biochemicals and materials.
As used herein, the term xe2x80x9carylxe2x80x9d means a monovalent monocyclic or bicyclic aromatic hydrocarbon radical of 6 to 10 ring atoms, and optionally substituted independently with one, two, three, four or five substituents selected from alkyl, haloalkyl, cycloalkyl, halo, nitro, cyano, xe2x80x94OR (where R is hydrogen, alkyl, haloalkyl, cycloalkyl, optionally substituted phenyl), acyl, and xe2x80x94COOR (where R is hydrogen or alkyl). More specifically the term aryl includes, but is not limited to, phenyl, 1-naphthyl, 2-naphthyl, and derivatives thereof.
As used herein, the term xe2x80x9cacylxe2x80x9d means a (xe2x80x94C(O)R1 group) aryl or aliphatic acyl groups where R1 is, e.g., a C1-5 lower alkyl. Examples of acyl include straight chain or branched alkanoyls such as formyl; acetyl, propanoyl, butanoyl, 2-methylpropanoyl, and pentanoyl. Preferably the acyl is acetyl.
In one embodiment of the invention, [2, 2-2H2, 2-13C]dithane can be made from [2H3, 13C]methyl phenyl sulfoxide in process as shown below. The [2, 2-2H2, 2-13C]dithane can be used as a non-volatile carrier of the desired carbon and hydrogen labels. 
Availability of the [2, 2-2H2, 2-13C]dithane will allow researchers to take advantage of the wealth of chemistry that has been done using unlabeled dithane.
The present invention provides efficient large scale processes for the preparation of [2, 2-2H2, 2-13C]dithane from [2H3, 13C]methyl phenyl sulfoxide. Dithane provides a chemically stable and non-volatile carrier for the valuable 13C and 2H labels.
In the process of the present invention, [2, 2-2H2,2-13C]dithane can be prepared in a high yield ( greater than 95%) process by first reacting [2H3, 13C]methyl phenyl sulfoxide with, e.g., a sodium acylate, preferably sodium acetate, in acetic anhydride to form an intermediate and reacting the intermediate with HSxe2x80x94(CH2)3xe2x80x94SH in methylene chloride to produce the dithane. Optionally, the dithane may be prepared with only a single deuterium atom on the 13C labeled atom by altering the deuterium substitution on the [13C]methyl phenyl sulfoxide.
The present invention is more particularly described in the following examples which are intended as illustrative only, since numerous modifications and variations will be apparent to those skilled in the art.